FERGUSON, Mo. -- Gov. Jay Nixon on Thursday ordered the Missouri National Guard to begin withdrawing from Ferguson, where nightly scenes of unrest have erupted since a white police officer fatally shot an unarmed black 18-year-old nearly two weeks ago.

Since the guard's arrival Monday, flare-ups in the small section of town that had been the center of nightly unrest have begun to subside. The quietest night was overnight Wednesday and Thursday, when police arrested only a handful of people in the protest zone.

"As we continue to see improvement, I have ordered the Missouri National Guard to begin a systematic process of withdrawing from the City of Ferguson," the governor said in a statement.

Demonstrations began after the Aug. 9 shooting of Michael Brown, and authorities have arrested at least 163 people in the protest area. Data provided Thursday by St. Louis County showed that while the majority of those arrested are Missourians, just seven live in Ferguson, a St. Louis suburb. The vast majority, 128 people, were cited for failure to disperse. Twenty-one face burglary-related charges.

Meanwhile Thursday, St. Louis County prosecutor Bob McCulloch reiterated he has no intentions of removing himself from the case.

Some question McCulloch's ability to be unbiased since his father, mother and other relatives worked for St. Louis police. His father was killed while responding to a call involving a black suspect.

Nixon said this week he is not asking McCulloch to recuse himself. But a McCulloch aide, Ed Magee, said the governor 'didn't take an actual position one way or the other."

A Nixon spokesman did not immediately return a message seeking comment.